The national electricity grid infrastructure began in the UK in the 1920s with the intention to distribute electricity from fossil fuel power stations across the nation.

The Orkney grid grew, as might be expected, from the main town of Kirkwall out through the parishes and eventually via submarine cables to the inhabited islands.

The Orkney Mainland was largely connected up to the Power Station in Kirkwall between 1947 and 1954, with the majority of the islands following from 1966, with Shapinsay. An outlier in this process was the island of Gairsay, which was actually the first island to receive mains electricity in 1951. The only two residents, a Mrs Coventry and her daughter, paid the thousands of pounds to have the cable laid by Kirkwall firm C Findlay & Sons. The last of the islands to be connected, North Ronaldsay, only received mains power via submarine cable in 1983, a full year after Orkney was connected to the National Grid.

That came in October of 1982, when the first 33 kV subsea cable across the Pentland Firth connected Orkney to the grid, running between Murkle Bay near Thurso and Rackwick Bay on Hoy, and onward across the Bring Deeps to Scorradale in Orphir. This meant that the diesel power station in Kirkwall became a backup generator in case of cable failure.

Then in 1998, increased demand, and the desire to reduce the use of the diesel generator, led to a second 33 kV subsea cable being installed. These cables have a maximum capacity between 34 MW and 40 MW. To put that into perspective, demand on the islands today ranges from 7 MW to 46 MW.  At this time Orkney residents experienced higher than average energy costs, around 2p extra per unit, due to the cost of connecting ‘remoter’ parts of the UK.

Undersea electricity cable connecting Orkney to the mainland © Laura Watts
Undersea electricity cable connecting Orkney to the mainland © Laura Watts
Rackwick cable landing (Credit Colin Keldie)

As early as 2001, with Orkney becoming an area rich in renewable energy resources, including onshore wind and marine energy, the National Grid struggled to accommodate the changes, as the cables were only meant to supply energy to the islands, not export.

Despite this, the restricted capacities have allowed Orkney to become a test site for multiple smart grid technologies. In 2006, Orkney became a Registered Power Zone (RPZ), an area of the National Grid network designated for the research, development, and demonstration of innovative solutions to managing capacity.

Then, in 2009 the UK’s first active network management (ANM) system was installed in the islands by Scottish and Southern Electricity Networks (SSEN), a smart grid system for balancing electricity generation with demand.

Orbital O2 tidal energy device (Credit Colin Keldie)
Wind turbines Orkney (Credit Colin Keldie)
Solar PV panels on Westrow Lodge Bed and Breakfast in Orphir

The active network management system

The ANM approach transformed the nationally-managed grid into regional systems that responded to local shifts in energy supply and demand.

The ANM works by switching off generators at peak generating times (e.g. when it was really windy) to avoid exceeding grid capacity. This allowed the connection of a further 22.4 MW of renewable energy devices to an electricity network at full capacity. Unfortunately, Orkney is still not able to harness its full renewable energy potential.

The system works by using live data to monitor how the network is operating. To ensure its safe operation, the network is divided into zones. Each zone represents a constraint point as a result of the additional generation. The ANM system will intervene when real time data relayed back to it exceeds any of the limits at these points.

The ANM uses a stacking basis, with a last-on, first-off arrangement. Those who signed up many years ago are at the bottom of the stack, and they get to stay on the longest. Those who joined later get switched off first when the energy supply is larger than the demand at the time.

The reality of this meant that in 2017, although Orkney generated 160.2 GWh from renewable energy, 77 GWh were exported to the grid, 24 GWh got curtailed, and the islands imported 4.7 GWh.

Orkney electric grid map

Grid connection ban

With the existing electricity distribution network in Orkney still operating at full capacity, an effective ban on new grid connections on the islands was put in place in 2012.

This applies to medium and larger energy generators, including “G59” connections of 50 kW or more, that normally had a different connection process to larger projects. Smaller “G83” connections, such as small turbines and household solar panels that generate 3.86kW or below per phase, are still being accepted in Orkney. This is because they are not connected to the ANM system.

Overall, the ban helped to avoid very high levels of curtailment for large wind generators, but the economic impact on many of the existing turbines cannot be underplayed.

Months of work by a Grid Steering Group led by Orkney Islands Council and including representatives from Orkney Renewable Energy Forum, Community Energy Scotland, Highlands and Islands Enterprise and Scottish and Southern Energy Power Distribution, sought solutions to accommodate further micro-generation connections on the Orkney network.

Although a future was seen in some of the emerging projects at a meeting of the group on 18th December 2012, the announcement three days later from Scottish Hydro Electric Transmission of likely delays to the proposed Northern Scotland transmission reinforcement plans; including the 132kV Orkney subsea cable that would have been key to many of the solutions to the grid capacity issues, was a blow that has resulted in severe negative economic impact to the islands, with the loss of an estimated billions of pounds of investment.

It may be that net zero targets will bring some of the projects shelved in 2012-13 back into focus though, with maximising electricity demand having been a strong theme. Crop drying, insect farming, a hot tub complex and provision of special heated accommodation for newborn calves were all thrown into the mix at that time, along with electrification of local authority and health service buildings.

Energy Storage

With current grid constraints, technologies are being trialled today to maximise the local use of renewable energy and store any excess. These include domestic scale batteries, green hydrogen, and creating flexibility in our demand for electricity. To find out more visit our webpage on energy storage.

Tesla powerwall Kirkwall (Credit Colin Keldie)
Jerry Gibson, EMEC operations technician, overview of EMEC hydrogen mobile storage unit (Credit Colin Keldie)
EV chargers

Opportunities

Looking forward, new infrastructure is needed to ensure Orkney, whose residents have always made the best use of the resources around their islands, can fully benefit from its valuable renewable resource. A project currently under consideration is Scottish and Southern Electricity Networks’ plans to enhance the power network within Orkney and lay a 220 MW capacity cable to the Scottish mainland in 2027/28. Ofgem gave provisional approval in March 2023 for this link to go ahead, with the original conditions of 135 MW of generating capacity coming online having largely been met.

Projects that will deliver 100 MW of renewable power are already lined up including commercial wind farms under development at Costa Head and Hesta Head, projected to deliver 40 MW, and Orkney Islands Council have scoped proposals for three additional community wind farms: on Hoy, on Faray, and at Quanterness, projected to deliver an additional 28.8 MW.